In the microelectronics industry, the trend is to reduce the size of structural features. Microlithography employing effective photoresists provides the enabling techniques. However, as the feature miniaturization continues, there is a need to decrease the photoresist thickness as well. For some lithographic imaging processes, the thin photoresist used in advance microlithography can no longer provide enough masking for the duration of etching in order to achieve the transfer of patterns to the substrate with high fidelity.
One solution to this problem is the utilization of a layer underlying the photoresist, which not only functions as anti-reflective coating, but also provides sufficient etch selectivity. This enhanced etch selectivity will allow this coating to be used as an image transfer intermediate. In the current state-of-the-art technology development, silicon-containing bottom anti-reflective coating is employed to serve this purpose in, for example, a trilayer scheme currently being developed by the semiconductor industry.
Despite the fact that the cured silicon-containing bottom antireflective coating/hardmask materials can be removed by dry etching employing plasma, it is very desirable that they can be removed by stripping or wet etching without damaging the substrate or IC devices. Currently, the stripper technology serves to remove organic materials. For example, U.S. Pat. Nos. 4,744,834, 4,395,479, 4,401,748, 4,428,871 disclose 2-pyrrolidone based stripping compositions useful for removing photoresists from substrates. U.S. Pat. Nos. 4,776,892 and 4,239,661 disclose aqueous stripping compositions containing an organic quaternary ammonium base. U.S. Pat. No. 3,673,099 and European Patent 0531292 are directed to stripping compositions containing a mixture of substituted 2-pyrrolidone and an organic quaternary ammonium base.
Cured silicon-oxygen containing materials behave differently from organic materials, as they are more similar to inorganic silicate structures. It has been shown that silicon-bottom antireflective coating materials can be removed by composition containing HF (Proceedings of SPIE 2005, vol. 5753, pp. 449-458). WO 2004/113417 A1 discloses silicon-containing bottom antireflective coating material with high HF etch rate. However, HF is extremely toxic and disposal of HF-containing stripper is also a problem.
The inventors have discovered that silicon-containing bottom antireflective coating materials can not be removed by stripper containing HF. Therefore, there is a need to develop a stripper for removal of silicon-oxygen containing bottom antireflective coating/hardmask materials